I just realized those examples don't use the algorithm for color because I added that later, anyway you can check the algorithm for color at line 1 of https://github.com/4skinSkywalker/SmartPrompt/blob/main/index.js, if you have a better way to choose colors computationally feel free to tell me.
I don't see the fixed positioning cutting off stuff, the modal is scrolling and that's fine... If you can tell me what you see it's cutting off, then I'll fix it.
The proper semantics is left to the consumer, infact you can inject any HTML. You can make the markup as semantic as you want really, this prompt is just an host for some form inputs with two buttons. Nothing special.
P.S.: I would like to talk to you. My Telegram handle is "FredoCorleone", or Discord "Fredo Corleone#0024". If you add me, then we can have a chat so that you can teach me about those pain points (accessibility, styling, ...) you seem to be good at.